The goal of this project is to evaluate a recently introduced method of rodent embryo culture for its suitability as a model system for basic studies in developmental biology and as a test system for potentially teratogenic compounds. This method permits in vitro development of rat or mouse embryos at normal rates for more than 48 hours, during which numerous developmental changes can be observed. Developmental studies will emphasize the sequence and timing of such biochemical markers as biosynthetic enzymes and cell surface receptors for various hormones and neurotransmitters. The efficacy of this system for the identification of teratogens will be examined using compounds known to cause birth defects; the approach will then be extended to suspected teratogens. The latter class of compounds will be compiled on the basis of certain physicochemical properties employing the predictive knowledge gained from previous studies in the Laboratory on the growth-inhibitory effects of various food additives, preservatives, antiseptics, and drugs on bacterial and mammalian cells in culture.